Surgical cartridge, pump and surgical operating machine

ABSTRACT

A surgical cartridge includes an inner plate; and an outer plate arranged approximately parallel to the inner plate. The flow paths between the inner plate and the outer plate are arranged to form an irrigation flow path for directing fluid towards the surgical site via an irrigation connection and an aspiration flow path for directing fluid away from the surgical site via an aspiration connection. The inner plate includes membranes adapted for cooperation with plungers and/or valves of a membrane pump. The membranes include a main membrane, at least two valve membranes and an auxiliary membrane adapted to cooperate with a main membrane plunger, valve and an auxiliary membrane plunger of the pump, respectively.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an irrigation/aspiration system for irrigatingand aspirating a surgical site.

Description of the Related Art

Irrigation/aspiration systems are known and are used during smallincision surgery, in particular during ophthalmic surgery. Theirrigation/aspiration system is arranged for directing fluid towards andfrom the eye during the surgery. The system is used for irrigation andaspiration of the eye and to maintain a controlled intraocular pressurein the eye during the surgery.

The irrigation/aspiration system typically comprises a pump for pumpingthe fluid to and/or from the surgical site. The pumps are usuallyarranged at the aspiration side of the system, but can also be arrangedin the irrigation side of the system. In the prior art, typically, twopump systems are known, i.e. either a pressure controlled pump or a flowcontrolled pump. Both pump systems have advantages and drawbacks.

A pressure controlled system typically comprises a vacuum pump or aventuri pump. An advantage of the pressure controlled pump is that thepressure, i.e. the underpressure or vacuum, in the system is well known.Also, the quick response time of the pressure controlled pump is highlyappreciated. A drawback of the pressure controlled pump is that flowinformation is not available. Flow is a result of the vacuum applied andthe resistance in the flow path, and a precise flow is difficult tocontrol.

A flow controlled system typically comprises a peristaltic pump. Anadvantage of the flow controlled system is the relatively stable flowrate. Another advantage is the stable flow, independent of the viscosityof the medium. During eye surgery the eye may be filled with acombination of air and liquid. The fluids may be of different viscosity.When using the vacuum pump of the pressure controlled system, theresulting flow will be different in air or water. A drawback of theexisting flow controlled systems is the relatively slow response timeand/or the fluctuations in the flow due to the peristaltic movement ofthe pump.

Therefore, typically either a pressure controlled pump or a flowcontrolled pump is used to operate in either a pressure controlled modeor a flow controlled mode. It is also known to provide a combined systemthat has both pumps, a flow controlled pump and a pressure controlledpump, as for example described in EP 1 900 347. A drawback of such asystem however is, that two separate pumps are required, resulting in arelatively voluminous apparatus. Further, switching between the pressurecontrolled mode and the flow controlled mode can be relatively complexand takes time.

There is a need for an irrigation/aspiration system that obviates atleast one of the above mentioned drawbacks. For example, there is a needfor an irrigation/aspiration system that allows operating in the flowcontrolled mode or the pressure controlled mode while maintaining theadvantages of either control mode.

SUMMARY OF THE INVENTION

Thereto, the invention provides for an irrigation/aspiration system forirrigating and aspirating a surgical site comprising an irrigation flowpath for directing fluid towards the surgical site via an irrigationconnection, and an aspiration flow path for directing fluid away fromthe surgical site via an aspiration connection, wherein in theirrigation flow path and/or the aspiration flow path a membrane pump isarranged for pumping fluid through the irrigation flow path and/or theaspiration flow path, wherein the membrane pump comprises a main pumpchamber, at least two valves for opening and/or closing the main pumpchamber and an auxiliary pump chamber arranged between the irrigationconnection and/or aspiration connection and the main pump chamber forcompensating movement of a main pump plunger element in the main pumpchamber to provide for an approximately smooth flow to and/or from thesurgical site.

By providing a membrane pump comprising a main pump chamber and anauxiliary pump chamber that is arranged between the main pump chamberand the surgical site, the pulsating movement of the main pump plungerelement in the main pump chamber can be compensated by the movement ofan auxiliary plunger element in the auxiliary pump chamber such that anapproximately smooth flow to/from the surgical site can be obtained.

By moving a main pump plunger element in the main pump chamber up anddown, a pulsation fluid flow is obtained. The flow can be known and isdependent on the velocity of the plunger element. The main pump chamberthen functions as a flow controlled pump alike a peristaltic pump,generating a pulsation fluid flow. By adding the auxiliary pump chamberto the main pump chamber of which an auxiliary pump plunger element cancompensate the movement of the main pump plunger element, anapproximately nearly smooth flow can be obtained, which is animprovement with respect to the known flow controlled pumps. Byproviding the auxiliary pump chamber the membrane pump can be operatedin a flow controlled mode and generating a nearly smooth flow, asopposed to the pulsating flow of the conventional peristaltic pumps.Since the flow rate is known, because the flow rate depends on thevelocity of the plunger elements, the membrane pump can be operated as aflow controlled pump. Further, by providing a system according to theinvention, the flow can be stable and independent of the viscosity ofthe fluid.

In the context of the invention, an approximately smooth flow isunderstood to be a nearly smooth flow, i.e. a flow with a nearly evenflow rate. An approximately or nearly smooth flow is understood to haveno or limited flow rate variations, as opposed to a pulsating flow ofprior art flow controlled pumps, such as peristaltic pumps.Advantageously, the flow obtained by a pump system according to theinvention is free of waves or pulses, as opposed to the flow of aconventional peristaltic pump which is inherently a wave flow orpulsating flow.

In addition, by providing a membrane pump with a main pump chamber andan auxiliary pump chamber, the flow of the membrane pump can berelatively quickly adapted by adapting the movement of the plungerelements. The response time of the membrane pump according to theinvention can therefore be relatively short compared to the responsetime of conventional flow controlled pumps, such as a peristaltic pump.

Advantageously, a control unit is provided to control the operation ofthe membrane pump, in particular to control the movement of the plungerelements and/or the valves. It is possible to provide for a mechanicalcontrol system, for example by providing the plunger elements and/orvalve elements on a camshaft the velocity of which can be varied toprovide for a higher or lower flow. Also, the cams on the camshaft canbe made velocity-dependent.

Alternatively, each plunger element and/or valve element may be operatedindividually by, for example, a direct drive motor. By providing acontrol unit that controls the direct drive motors, the plunger and/orvalve elements can be operated individually in velocity and positionsuch that the flow can be optimally and relatively accuratelycontrolled.

By providing a pressure sensor that is adapted to establish the pressurein the system, the pressure can be known. When the pressure value isknown, the pressure can be used as a control parameter and it may becomepossible to operate the system as a pressure controlled system.

When the pressure is known, and the flow in the system is known as well,the system can be controlled on the pressure and/or on the flow, so itcan be operated as a pressure controlled system or as a flow controlledsystem having the advantages of an approximately smooth flow and of arelatively quick response time.

In a pressure controlled mode, the pressure value can be used as aninput to the control unit that may adapt the control of the plungerand/or valve elements depending on the desired pressure value.

During a surgical procedure, the surgeon may like to use the system in afirst step in a pressure controlled mode and in a second step in a flowcontrolled mode. For example, in the first step eye fluid may be removedrelatively fast from the eye using maximum flow and pressure control. Inthe second step, the flow may be limited and control of the flow becomesimportant, for example when approaching the retina. When using thesystem according to the invention, a relatively simple switch betweenthe flow controlled mode and the pressure controlled mode is possible,complex switching mechanisms between two separate pumps can be obviated.In addition, when using the pump according to the invention, the flowand the pressure in the system may be known, allowing relativelyaccurate operating and controlling of the pump. Furthermore, by using amembrane pump according to the invention, a relatively quick responsetime can be obtained.

It is understood that a pump system comprising a main pump chamber witha main pump plunger element with at least two valves for opening and/orclosing of the main pump chamber, further comprising an auxiliary pumpchamber with an auxiliary pump plunger element that is at one side influid connection with the main pump chamber, wherein the auxiliary pumpplunger element is arranged to compensate movement of the main pumpplunger element to provide for an approximately even fluid flow at aside of the auxiliary pump chamber opposite the main pump chamber can beconsidered as an invention on its own. By providing an auxiliary pumpchamber with an auxiliary pump plunger element, the pulsating movementof the main pump chamber can be compensated such that an approximatelyeven flow can be obtained as compared to the pulsating flow of the mainpump chamber. The auxiliary pump plunger element moves in antiphase withrespect to the main pump plunger element as to obtain the compensatingmovement and the approximately even flow.

In another aspect of the invention, the membrane pump comprises plungerelements that are arranged to provide an underpressure between amembrane body and a plunger element. By providing an underpressure, alsocalled vacuum pressure, between the membrane body and the plungerelement, the membrane body is sucked against the plunger element. Whenmoving the plunger element, the membrane body is moved as well and thepump chamber can thus become larger or smaller.

It is understood that the aspect of a plunger element providing anunderpressure between the plunger element and the membrane body suchthat the membrane body is sucked against the plunger element, can beconsidered as an invention on its own. Contrary to a prior art membranepump in which the membrane is moved by the pushing action of a plungeragainst the membrane, the membrane is now moved by the plunger elementdue to suction contact between the plunger element and the membrane.According to this aspect of the invention, the membrane body is suckedagainst the plunger element and is thus, during operation, in permanentcontact with the plunger element. Movement of the plunger element causesmovement of the membrane body. This allows a more accurate control ofthe movement of the membrane body and thus of the volume of the pumpchamber.

To provide an underpressure or vacuum between the plunger element andthe membrane body, the plunger element may be provided with a hollowbore or channel that that ends in an underside of the plunger elementfacing the membrane body. By providing an underpressure through the boreor channel, the membrane body is sucked against the underside of theplunger element. The underpressure between the plunger element and themembrane body is relatively high, for example the absolute pressure maybe between approximately 15-75 mmHg, preferably approximately between20-60 mmHg. Such a relatively low pressure is also referred to as avacuum pressure. Advantageously, the irrigation/aspiration systemcomprises a cartridge in which the irrigation flow path and theaspiration flow path are arranged and a pump unit for cooperation withthe cartridge. By providing a cartridge and a pump unit, a modularsystem can be obtained. The cartridge can be provided as a one-way orthrow-away article, while the pump unit may be of a more permanentnature, for example arranged in a surgical operating machine. Byproviding a cartridge, the cartridge can be made relatively easilysterile, such that the flow paths in the cartridge can be sterile aswell.

Advantageously, the flow paths in the cartridge are rigid in which themembrane bodies are arranged. Contrary to the rigid flow paths, themembrane bodies are flexible. This is also contrary to a prior artperistaltic pump or prior art cassette for a peristaltic pump thatusually requires at least part of the flow path to be flexible that isin engagement with the peristaltic pump.

According to an aspect of the invention, the surgical cartridgecomprises an inner plate and an outer plate arranged approximatelyparallel to the inner plate, wherein between the inner plate and theouter plate flow paths are arranged forming an irrigation flow path fordirecting fluid towards the surgical site via an irrigation connectionand an aspiration flow path for directing fluid away from the surgicalsite via an aspiration connection, wherein the inner plate comprisesmembrane bodies adapted for cooperation with plunger elements and/orvalve elements of a membrane pump unit, wherein the membrane bodiescomprise a main membrane body, at least two valve membrane bodies and anauxiliary membrane body adapted to cooperate with a main membraneplunger element, valve elements and an auxiliary membrane plungerelement of the pump unit respectively.

By providing the flow paths in the cartridge, the flow paths aredetermined and the cartridge is relatively fast ready to use. Only theirrigation line and the aspiration line need to be connected to theirrigation connection and the aspiration connection to obtain aconnection to and from the surgical site. The inner plate and the outerplate may be of relatively hard plastic parts that may be weldedtogether to form closed channels, the fluid flow path, and chambers. Atsome positions, a wall part of the channels and/or chambers is made ofan elastic material forming a membrane.

In addition, by providing an inner plate in which the membrane bodiesare arranged, the cooperation with the pump unit can be relativelyeasily be established. By coupling the cartridge to the pump unit, theplunger and/or valve elements of the pump unit are facing theirrespective membrane bodies. This allows for easy manipulating of thecartridge to the pump unit. Furthermore, the thus obtainedirrigation/aspiration is less sensitive to fabrication tolerances of thecartridge.

In an advantageous embodiment, the cartridge is provided with a sealingedge for sealingly coupling to the pump unit. The sealing edge enclosesthe inner plate and by coupling the cartridge to the pump unit, thesealing edge seals of the chamber between the inner plate and the pumpunit. By sealingly coupling the cartridge to the pump unit, the chamberbetween the inner plate and the pump unit can be put at an underpressureto suck the cartridge against the pump unit. This is also known as‘vacuum clamping’ the cartridge to the pump unit. Preferably, theunderpressure in the chamber between the inner plate and the pump unitis maintained during the use of the cartridge on the pump unit toprovide for a firm coupling of the cartridge to the pump unit. Due tothe vacuum clamping, a firm contact between the hard inner plate of thecartridge and the pump unit may be established which may increaseactuation accuracy.

Typically, the cartridge may in addition be provided with couplingelements, such as click fingers, or hooks, or pins or ratchets, etc. toinitially couple with the pump unit as well to provide for additionalsafety. During use, the cartridge will first be coupled to the pump unitby means of the coupling elements. Then, the cartridge is already wellpositioned and centred in front of the pump unit. Secondly, anunderpressure will be provided between the cartridge and the pump unitto sealingly suck the cartridge to the pump unit. Therefore, also incase of a power breakdown, when the vacuum falls away, the cartridgeremains coupled to the pump unit by means of the coupling elements.

According to another aspect of the invention, the pump unit comprisesplunger elements and valve elements for cooperation with membrane bodiesto provide for a membrane pump, wherein the plunger elements comprise amain plunger element and an auxiliary plunger element for cooperationwith a main membrane body and an auxiliary membrane body respectively.

According to another aspect of the invention, the pressure sensor can beprovided as sensor external to the cartridge cooperating with a membraneon the cartridge.

In a cartridge, fluid paths are arranged and in a wall of such a fluidpath, a membrane can be provided. The membrane typically is relativelythin and flexible, one side of the membrane is at the inner side of thefluid flow path and an other side of the membrane is at the outer sideof the fluid flow path. Preferably, the membrane is arranged in a sidewall of the flow path. Thus, the side of the membrane inside the fluidflow path, i.e. the inner side of the membrane, is in contact with thefluid. The other side of the membrane outside the fluid flow path, i.e.the outer side of the membrane is not in contact with the fluid.According to this aspect of the invention, a pressure sensor is nowprovided that cooperates with the outer side of the membrane. Thepressure sensor then measures the pressure of the fluid on the membrane.Therefore, the pressure sensor itself external to the cartridge and isnot in contact with the fluid. The membrane is very compliant comparedto the pressure sensor and has therefore no significant influence on thepressure measurement inside the cartridge.

This is contrary to the prior art pressure measurements. According tothe prior art, the cartridge itself is provided with a pressure sensorthat is arranged partially inside the fluid flow path of the cartridge.Thus, the pressure sensor is in contact with fluid, which requirescomplex and expensive sealing. Also, the cartridge is a throw-awaydisposable article, such that, when disposing the cartridge, thepressure sensor is thrown away as well. This results in a relativelyexpensive cartridge.

By providing the pressure sensor outside the cartridge, e.g. in the pumpunit or on the operating machine, the pressure sensor can cooperate witha membrane in the fluid flow path of the cartridge. This may result in amore cost effective manufacturing of the cartridge, since it can beprovided without the pressure sensor. Also, since the pressure sensor onthe cartridge is now absent, the cartridge can become thinner, therebyreducing packaging, storage and transport costs. Furthermore, thepressure sensor itself may be of a more cost effective type, since thepressure sensor is not in contact with fluid.

Advantageously, the pressure sensor is a load cell sensor measuring thedisplacement of the membrane and translating this displacement into aforce or pressure load.

This aspect of the pressure sensor can be considered as an invention onits own.

The invention further relates to a surgical operating machine comprisinga pump unit.

The invention also relates to a method for operating anirrigation/aspiration system, wherein the auxiliary pump chamber isoperated in antiphase with respect to the main pump chamber to providefor an approximately smooth flow.

By moving the main plunger element up and down, fluid is pumped throughthe flow path in a pulsating way. When the main pump chamber is filled,an inlet valve closes and an outlet valve of the main pump chamber opensto allow the fluid to flow away due to the downwards movement of themain pump plunger element. In the mean time the auxiliary pump plungertakes over the flow task by moving upwards. After emptying the main pumpchamber, the outlet valve closes and the inlet valve opens again, andthe main pump plunger element moves up to allow filling the main pumpchamber. When the main pump plunger element moves upwards, the auxiliarypump plunger element moves downward. The auxiliary pump plunger elementand the main pump plunger element therefore operate in antiphase tocompensate for the fluctuations of the main pump plunger element, suchthat an approximately smooth flow is obtained, such that there is anapproximately smooth flow to and/or from the surgical site.

Further advantageous embodiments are represented in the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will further be elucidated on the basis of exemplaryembodiments which are represented in the drawings. The exemplaryembodiments are given by way of non-limitative illustration of theinvention.

In the drawings:

FIG. 1 shows a schematic representation in four steps of the operationof the membrane pump according to the invention;

FIG. 2 shows a schematic perspective exploded view of anirrigation/aspiration system according to the invention;

FIG. 3 shows a schematic perspective rear view of part of the pump unitand of the cartridge according to the invention;

FIG. 4 shows a schematic exploded view of a cartridge according to theinvention;

FIG. 5 shows a schematic front view of a cartridge according to theinvention;

FIG. 6 shows a schematic front view of a cartridge according to theinvention showing the fluid flow from infusion bag to collection bag;and

FIG. 7a and FIG. 7b show in a schematic perspective cross-sectional viewthe construction of a valve, in open and closed condition respectively,according to an aspect of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

It is noted that the figures are only schematic representations ofembodiments of the invention that are given by way of non-limitingexample. In the figures, the same or corresponding parts are designatedwith the same reference numerals.

FIG. 1 shows a schematic representation of a pump 1 according to theinvention. The pump 1 is here arranged in an aspiration flow path A ofan irrigation/aspiration system. In the aspiration flow path A, thefluid comes from the eye E and goes to a collection bag C. It is evidentthat the pump 1 can also be arranged in an irrigation flow path.

Pump 1 comprises a main pump chamber 2 with a main pump plunger element3. The main pump chamber 2 can be opened and closed by a first valve 4and a second valve 5. Upstream of the main pump chamber 2, an auxiliarypump chamber 6 is arranged with an auxiliary pump plunger element 7. Inthis embodiment, the main and auxiliary pump plunger elements 3, 7 andthe first and second valves 4, 5 are operated by cams 8 on a camshaft 9.

The operation of the pump 1 will now be elucidated using four figuresFIG. 1a -FIG. 1d each depicting one step. It may be clear that themovement of the plunger elements 3, 7 and of the valves 4, 5 isapproximately continuous and more or less steps may be visualized.

In a first step, shown in FIG. 1a , the main pump plunger element 3moves upwardly, thereby pumping fluid out of the eye E towards theauxiliary pump chamber 6 and main pump chamber 2 while the valve 4 isopen. The second valve 5 is closed. Simultaneously, the auxiliary pumpplunger element 7 moves downwardly and so decreasing the amount ofvolume. However, the auxiliary pump plunger element 7 moves slower thanmain pump plunger element 3 resulting in a smooth flow out of the eye.At the end of this step, the main pump chamber 2 is now maximally filledwith fluid, while the auxiliary pump chamber 6 is almost empty.

In step 2, as shown in FIG. 1b , the first valve 4 is closed, and thesecond valve 5 is opened. The auxiliary pump plunger 7 is movingupwards, generating an aspiration flow towards the auxiliary pumpchamber 6.

In step 3, as shown in FIG. 1c , by moving the main pump plunger element3 downwardly, fluid is pumped out of the main pump chamber 3 towards thecollection bag C. This releasing of the fluid into the aspiration flowpath A towards the collection bag C is done in a pulsating movement.This is however not a problem, since this released fluid goes to thecollection bag C. In the mean time, the auxiliary pump plunger 7 ismoving upwards, generating an aspiration flow towards the auxiliary pumpchamber 6. At the end of this step, the main pump chamber 3 is empty.

In step 4, as shown in FIG. 1d , the second valve 5 is closed, and thefirst valve 4 is opened. The auxiliary pump plunger 7 is moving upwards,generating an aspiration flow towards the auxiliary pump chamber 6.

Due to the provision of auxiliary pump chamber 6 with auxiliary pumpplunger 7, the pulsating flow of the main pump chamber 2 can becompensated, such that fluid is aspirated out of the eye E in a nearlyeven volume. The auxiliary pump plunger element 7 in fact compensatesthe movement of the main pump plunger element 3 and thus an almostsmooth fluid flow aspirated out of the eye E can be obtained. Thecompensating movement of the auxiliary pump plunger element 7 isobtained by moving the auxiliary pump plunger element 7 in antiphasewith respect to the main pump plunger element 3.

By varying the velocity of the camshaft 9, the fluid flow F can bevaried as well. Also, the cams 8 can be made velocity-dependent.

Alternatively to the cams 8 and the camshaft 9, the plunger elements 3,7 and the valves 4, 5 can be controlled individually and independentlyfrom each other, for example when using direct drive motors. Then, eachplunger element 3, 7 and each valve 4, 5 is controlled by its own directdrive motor.

The pump 1 according to the invention therefore not only provides for aquick response time, but also provides for an approximately even fluidflow F out of the eye E. By varying the velocity of the camshaft 9, thevelocity of the plunger elements 3, 7 and valves 4, 5 is adjustedinstantaneously, providing for a quick response time. Also when usingdirect drive motors, varying the rpm of a direct drive motorinstantaneously influences the movement of the respective plunger and/orvalve body. Further, by providing the auxiliary pump chamber 6 with theauxiliary pump plunger element 7, the fluid flow F can becomeapproximately even, i.e. substantially without pulsations, as comparedto the fluid flow of e.g. a peristaltic pump.

FIG. 2 shows a schematic perspective view of a pump system 10 accordingto the invention. In particular, FIG. 2 shows an embodiment of anirrigation/aspiration system 10 for use in surgical applications, suchas for small incision surgery in for example the eye. Theirrigation/aspiration system 10 is then arranged for irrigating andaspirating a surgical site.

The pump system 10 comprises in this embodiment two main parts, a pumpunit 11 and a cartridge 12. The pump unit 11 and the cartridge 12 areshown at a distance from each other, but are in operation coupled toeach other. Typically, the pump unit 11 forms part of a larger entitysuch as a surgical operating machine. Such a machine is usually providedin an operating room.

The pump system 10 comprises a pump 1, more specifically in thisembodiment, a membrane pump 1. The membranes of the membrane pump 1 areprovided in the cartridge 12 and the plunger elements are provided onthe pump unit 11. In coupled state, they work together to form the pump1. The pump 1 functions as explained in relation to FIG. 1a -FIG. 1 d.

In FIG. 2 the pump plunger elements 3, 7 are visible. Here, the pumpplunger elements 3, 7 are arranged to provide an underpressure between amembrane body and the pump plunger element 3, 7. Thereto, the pumpplunger element 3, 7 is provided with a small bore 13, 14 approximatelyin the centre of the pump plunger element 3, 7. Through this bore 13, 14an underpressure is created between the membrane body and the pumpplunger element such that the membrane body is sucked against the pumpplunger element. Thus, by moving the pump plunger element, the membranebody is moved as well, thereby the volume of a pump chamber can bevaried.

FIG. 3 shows a perspective rear view of the surgical cartridge 12 at adistance of part of the pump unit 11. The surgical cartridge 12comprises an inner plate 15 and an outer plate 16. The outer plate 16 isarranged approximately parallel to the inner plate 15 such that betweenthe inner plate 15 and the outer plate 16 flow paths I, A can bearranged. The flow paths I, A are better visible in FIG. 5 and FIG. 6.The outer plate 16 is preferably made from relatively rigid plasticmaterial, as well as the inner plate 15. Advantageously, they are weldedtogether.

Further, the inner plate 15 is provided with relatively flexibleelements forming membrane bodies. An auxiliary membrane body 17 and amain membrane body 18 are provided that cooperate with auxiliary pumpplunger element 7 and main pump plunger element 3 respectively. Firstand second valves 4, 5 comprise a first valve element 19 and a firstvalve body 20 and a second valve element 21 and a second valve body 22respectively. The valve bodies 20, 22 are membrane bodies and areflexible as compared to the rigid inner plate 15. An embodiment of thevalve construction is shown in FIG. 6.

The pump system 10 further comprises at least one pressure sensor 23.Here, the pressure sensor 23 comprises a pressure element 24 and amembrane pressure body 25. The membrane pressure body 25 is in fluidcontact with the fluid flow path I, A and the pressure element 24 thenmeasures the force and/or displacement of the membrane pressure body 25as to establish the pressure in the fluid flow path I, A.Advantageously, the membrane pressure body 25 is arranged in the fluidflow path I, A. The membrane pressure body 25 has an inner side which isin contact with the fluid flowing through the flow path I, A and has anouter side facing away from the fluid flow path I, A at the outside ofthe fluid flow path I, A. The outer side of the membrane pressure body25 is in contact with the pressure element 24. The pressure element 24therefore does not form part of the cartridge 12, but can be arranged infor example the pump unit 11, as in this example.

Of course, in relation to other cartridges the pressure element 24 canbe arranged elsewhere on the operating machine for cooperation with thepressure membrane body 25. The cartridge 12 can thus be more lightweightand/or more cost effective and/or more thin when the pressure sensor canbe omitted. Also, since the cartridge 12 is a disposable article, arelative expensive pressure sensor does not have to be thrown awaytogether with the cartridge 12, but can remain on the pump unit for usewith a subsequent cartridge 12. This is contrary to the prior artwherein the pressure sensor forms part of the disposable cartridge.

According to an aspect of the invention, the pressure element 24 is aload cell element that can measure the displacement of the pressure bodymembrane 25 and translate the measured displacement into a force value.

The surgical cartridge 12 further comprises coupling elements 26 thatare arranged for cooperation with coupling elements, not shown here, onthe pump unit 11. The cartridge 12 typically is a one-way or throw-awayproduct, while the pump unit 11 remains. The cartridge 12 can then becoupled before use to the pump unit 11 and after the surgical use, thecartridge 12 can be removed from the pump unit 11 and be thrown away.Also, by providing the cartridge 12 as a throw-away article, thecartridge 12 can easily be sterilised.

The cartridge 12 is in this embodiment also provided with a sealing edge27 for sealingly couple to the pump unit 11. When connecting thecartridge 12 to the pump unit 11 via the coupling elements 26, a spaceis created between the inner plate 15 and the pump unit 11 which thesealing edge 27 sealingly closes off. This space can then be providedwith an underpressure such that the cartridge 12 is being sucked towardsthe pump unit 11. This underpressure in fact provides for a firm, andadditional to the coupling elements 26, connection of the cartridge 12to the pump unit 11. The cartridge 12 is firstly coupled to the pumpunit 11 via the coupling elements 26 to provide for initial couplingand/or centring of the cartridge 12 with respect to the pump unit 11.Then, secondly, the space between the inner plate 15 and pump unit 11 isset to an underpressure that may be in range of approximately 15-75 mmHGabsolute pressure to firmly fixate the cartridge 12 to the pump unit 11during the operation. This firm fixation may allow more accurateactuation of the plunger elements 3, 7 and/or the valve elements.

FIG. 4 shows a schematic perspective exploded view of the cartridge 12according to the invention. The inner plate 15 and the outer plate 16are usually made from relatively hard plastic material and can be weldedtogether. It can be seen that the outer plate 16 is provided with ribsforming the flow paths I, A once the outer plate 16 is engaged with theinner plate 15. In the inner plate 15, cut-aways 42 are provided inwhich flexible membranes fit. The membranes, here pressure membranebodies 25, valve membrane bodies 22, 20, 37A, 38A and 40A, membranebodies 17, 18, are usually made from a flexible, elastic material, e.g.an elastic thermoplastic material. The membranes face at one side, theinner side, the flow path and form in this embodiment part of the wallof the flow path, and face at another side, the outer side, away fromthe flow path. The membranes are with their inner side in fluid contactwith the fluid flowing through the flow path and are with their outerside in contact with the plunger element or valve element operatingthem.

The sealing edge 27 allows to vacuum couple the cartridge 12 to the pumpunit 11. Further, the outer plate 16 is provided with a handle bar 41for manually manoeuvring the cartridge 12.

In addition, the connections, 29, 31, 33, for the flow lines areprovided at the outer plate 16. Further, connections 34 are provided tohang a collection bag C onto.

A person wanting to use the cartridge 12 will grab it at the handle bar41 and will first couple it with the coupling elements 26 to the pumpunit 11. Then the underpressure can be provided to vacuum couple thecartridge 12 to the pump unit 11. The coupling elements thus provide foradditional safety, because in case of power shutdown, the underpressuredissolves and thus the vacuum coupling is undone. However, due to thecoupling elements 26, the cartridge 12 remains coupled to the pump unit11, so a safe situation remains.

FIG. 5 and FIG. 6 show a schematic front view of the cartridge 12according to the invention, wherein in FIG. 5 also the flow path isindicated.

From an infusion bag D an infusion line 28 goes to the cartridge 12. Theinfusion line 28 is connected to the cartridge at the infusion lineconnection 29. Then, the fluid flows through the irrigation path I inthe cartridge 12 towards the eye E. Between the irrigation flow path Iand the eye E, the irrigation line 30 is provided. The irrigation line30 is connected to the cartridge at the irrigation connection 31. Fromthe eye E to the cartridge 12, there is an aspiration line 32 toaspirate the fluid from the eye E. The aspiration line 32 is connectedto the cartridge at the aspiration connection 33. In this embodiment,the aspiration connection 33 is provided twice. Then the fluid flowsinto the aspiration flow path A in the cartridge 12 towards thecollection bag C. The collection bag C is connected to the cartridge atleast at the collection bag connection 34. The fluid may then flowdirectly into the collection bag or a collection bag line may beconnected between the cartridge 12 which ends into the collection bag.

Following the fluid flow from the infusion connection 29 in theirrigation flow path I, the fluid passes an infusion valve 35 foropening/closing the fluid flow coming from the infusion bag D.

Then the fluid passes a pressure sensor 36 to determine the pressure inthe irrigation flow path I. Prior to entering the irrigation line 30 viathe irrigation connection 31, there is an irrigation valve 37 providedto open/close the irrigation line. Fluid aspirated from the eye E passesthe aspiration valve 38 before flowing towards the pump 1. The pump 1comprises, as set out in relation to FIG. 2, an auxiliary pump chamber6, a first valve 4, a main pump chamber 2 and a second valve 5. Further,a pressure sensor 23 is provided to determine the pressure in theauxiliary pump chamber 6 and a pressure sensor 39 is provided todetermine the pressure in the main pump chamber 2.

Between the irrigation flow path I and the aspiration flow path A, abackflush flow path B with a backflush valve 40. The backflush valve 40can be opened when the surgeon may require additional fluid from theinfusion bag D at the surgical site. This fluid can then enter the eyevia the backflush flow path B and the aspiration line 32. The irrigationvalve 37 is in that case closed and the pump 1 is then stopped to allowthe backflush fluid towards the eye.

An advantage of the system 10 according to the invention, and inparticular of the embodiment shown in FIG. 6, is that there will befluid pressure onto the eye, also in case of a power shutdown. In caseof a power shutdown, the pump is not functioning anymore and the valveswill go to their open condition towards which they are pretensioned. Atleast the infusion valve 35 will remain in the open position. Since theinfusion bag D is positioned higher than the eye E, fluid will flow fromthe infusion bag D towards the eye E along the open valves 35, 37. Thepressure on the eye E will thus be somewhat higher than ambientpressure, i.e. ambient pressure and the pressure of the fluid columnbetween the eye E and the infusion bag D. By keeping pressure onto theeye E, also in case of a power shutdown, there is, during operation, asafe situation.

Advantageously, a control unit is provided in the pump unit 11 tocontrol the operation of the pump 1. Usually, the surgeon will prior orduring the surgical operation give settings to the surgical machine, forexample of the flow and/or underpressure required. These settings arethen inputted to the control unit which then controls the pump to obtainthe required settings. Since pressure sensors are available, not onlythe flow in the system 10 is known, but also the pressure such that thesystem 10 can operate both as a flow controlled system as well as apressure controlled system. The system 10 can thus easily be operated asa flow controlled system or as a pressure controlled system, sinceswitching between both operating modes is a mere setting in the controlunit. In addition the system 10 has relative short response times.

For example, by providing the pressure sensor 39 in addition to thepressure sensor 23, the pressure values of both sensors 39, 23 can becompared by the control unit. The control unit may then operate thevalve 4 between the pump chambers 6, 2 only when the pressure in bothpump chambers 6, 2 is equal, such that only controlled flow between bothchambers 6, 2 is provided to obtain a flow as smooth as possible out ofthe eye E.

FIGS. 7A and 7B show schematically the construction of a valve Vaccording to the invention. FIG. 7A shows the valve V in open conditionand FIG. 7B shows the valve V in closed condition. The construction ofthe valve V can be considered as another aspect of the invention. Valves4, 5, 35, 37 or 38 can be constructed according to the valveconstruction shown in FIG. 7. Valve V comprises a valve body VB and avalve element VE. The valve element VE operates the valve body VB.According to the invention, the valve body VB is a membrane body whichis flexible and pretensioned towards the open condition. In the opencondition, the valve body VB is concave. In a flow channel FC, such asthe flow path A of the system 10, a baffle plate BA is provided.Typically, the baffle plate BA is approximately as high as the height ofthe flow channel FC. Due to the concave valve body VB, there is adistance between an upper side of the baffle plate BA and the valve bodyVB such that the flow channel FC is open in the open condition of thevalve V and fluid can pass along the baffle plate BA. In the closedcondition of the valve V, as shown in FIG. 6b , the valve element VEoperates the valve body VB and presses the valve body VB against thebaffle plate BA to close the flow channel FC. By moving the valveelement VE, for example, a plunger element, upwards and downwards thevalve body VB can be operated. The valve body VB can thus be pressedagainst the baffle plate BA to close the flow channel FC or be releasedfrom the baffle plate BA to open the flow channel FC. Advantageously,the valve element VE is provided in the system 10 according to theinvention and/or is being operated by the control unit of the system 10.

According to a further aspect of the invention, the connections 29, 31and 33 are all three different connections. Preferably, the connections29, 31, 33 have different colours, and more preferably, are of differentconstruction. The connections are arranged such that the infusion flowline 28 can only connect to the infusion connection 29 and does not fitto the other connections 31, 33. Also, the irrigation flow line 30 canonly connect with the irrigation connection 31 and not with the otherconnections 29, 33. Also, the aspiration flow line 32 can only connectwith the aspiration connection 33 and not with the other connections 29,31. This allows minimizing of mistakes and a more safe and reliableoperation of the system 10. By providing each of the connections 29, 31,33 of a different size and/or construction and/or of a different colour,that corresponds with the construction and/or colour of the connectionof the flow line mistakes in connecting the flow lines to the connectionpoints may be minimized and preferably avoided. This may result in amore failure free operation of the system 10 and/or of the surgicaloperating machine. The valve construction may be considered as aninvention on its own as well.

Many variants will be apparent to the person skilled in the art. Allvariants are understood to be comprised within the scope of theinvention defined in the following claims.

What is claimed is:
 1. A surgical cartridge comprising: an inner plate;and an outer plate arranged approximately parallel to the inner plate,wherein between the inner plate and the outer plate flow paths arearranged forming an irrigation flow path for directing fluid towards thesurgical site via an irrigation connection and an aspiration flow pathfor directing fluid away from the surgical site via an aspirationconnection, wherein the inner plate comprises membranes adapted forcooperation with plungers and/or valves of a membrane pump, and whereinthe membranes comprise a main membrane, at least two valve membranes andan auxiliary membrane adapted to cooperate with a main membrane plunger,valves and an auxiliary membrane plunger of the pump respectively. 2.The surgical cartridge according to claim 1, wherein the main membraneoperates in a main pump chamber of the membrane pump and wherein theauxiliary membrane operates in an auxiliary pump chamber of the membranepump, and wherein further the auxiliary pump chamber is arranged betweenthe irrigation connection and/or aspiration connection and the main pumpchamber.
 3. The surgical cartridge according to claim 1, furthercomprising membranes for cooperation with pressure sensors of the pump.4. The surgical cartridge according to claim 1, wherein the inner plateis provided with a sealing edge for sealingly coupling to the pump. 5.The surgical cartridge according to claim 1, wherein the outer plate isprovided with an infusion bag connection and/or a collection bagconnection and/or the irrigation connection and/or the aspirationconnection.
 6. The surgical cartridge according to claim 1, wherein thesurgical cartridge is sterile.
 7. A pump comprising plungers and valvesfor cooperation with membranes to provide for a membrane pump, whereinthe plungers comprise a main plunger and an auxiliary plunger forcooperation with a main membrane and an auxiliary membrane respectively.8. The pump according to claim 7, wherein the main membrane and the mainplunger operate in a main pump chamber of the pump, and wherein theauxiliary membrane and auxiliary plunger operate in an auxiliary pumpchamber of the pump, and wherein further the auxiliary pump chamber isarranged between the irrigation connection and/or aspiration connectionand the main pump chamber.
 9. The pump according to claim 7, wherein theplungers are arranged to provide an underpressure between the membranes.10. The pump according to claim 7, further comprising pressure sensorsfor cooperation with pressure membranes.
 11. The pump according to claim7, wherein the pump is configured to cooperate with a surgicalcartridge, said surgical cartridge comprising: an inner plate; and anouter plate arranged approximately parallel to the inner plate, whereinbetween the inner plate and the outer plate flow paths are arrangedforming an irrigation flow path for directing fluid towards the surgicalsite via an irrigation connection and an aspiration flow path fordirecting fluid away from the surgical site via an aspirationconnection, wherein the inner plate comprises membranes adapted forcooperation with plungers and/or valves of a membrane pump, and whereinthe membranes comprise a main membrane, at least two valve membranes andan auxiliary membrane adapted to cooperate with a main membrane plunger,valves and an auxiliary membrane plunger of the pump respectively.
 12. Asurgical operating machine comprising the pump according to claim 7.